<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // var str = 'dhjiidjiuuhdujinuydnugdyuyndndn';
        // var index = -1;
        // var sum = 0;
        // while (true) {
        //     if (str.indexOf('d', index + 1) > -1) {
        //         sum++;
        //         index = str.indexOf('d', index + 1);
        //     } else {
        //         break;
        //     }
        // }
        console.log(sum);
        var str = 'abcoefoxyozzpp';
        var num = 0;
        var index = str.indexOf('o');
        while (index !== -1) {
            console.log(index);
            num++;
            index = str.indexOf('o', index + 1);
        }
        console.log(`o出现的次数是${num}次`);
    </script>
</body>
</html>